In response to the relative dearth of economic analyses of prevention programs, the proposed project will provide a cost-of-illness or social cost study of the Fast Track (FT) intervention. FT is an ongoing multi-site randomized trial designed to prevent the onset of serious conduct disorder and its concomitants in adolescence. The potential benefits include reductions in substance abuse and other behaviors that are costly to the participants, their families and society. The intervention is the focus of an ongoing evaluation being conducted at four sites-Nashville, Tennessee; rural Pennsylvania; Seattle, Washington; and Durham, North Carolina. The evaluation focuses on the experiences of 891 high-risk children living in high-poverty areas. These children were randomly assigned to intervention or control groups and are being followed over time. The ongoing ten-year evaluation involves information collected from the child?s teacher, parents, tutors, mentors, peers, and the child him- or herself. Evidence to date suggests that Fast Track produces real benefits for its participants. After the first seven years, the intervention promotes academic and social-cognitive skills and reduces conduct problem behaviors and special education placements. The proposed project will last five years. because the participants in FT are currently completing grades 8, 9, or 10, the next five years are the optimal time to conduct an economic analysis. The proposed project has four specific aims: (1) identify the impact of Fast Track on the costs of illness for the high-risk children participating in the study that have occurred or will occur through the first 14 years of the study; (2) calculate cost-effectiveness ratios for key outcomes, including measures of mental health status, delinquency, teenage pregnancy, drug and alcohol use, and sexually transmitted diseases as well as a measure of quality of life and of the impact on care givers? well-being; (3) project the future costs of illness for study participants (when the participants are age 20 or older); (4) identify subgroups of participants for whom the benefits of the intervention are especially large or small. The requested funds would be used to support the following activities: (1) analyses of the relevant outcomes from the evaluation data (such as drug use and use of mental health services); (2) continued reviews of agency and provider records; (3) collection and analysis of budgetary information (e.g., from school districts) required to estimate the dollar costs of the services involved (e.g., special education); (4) collection and processing of administrative data (e.g., on welfare receipt); (5) development and estimation of statistical models used to predict future social costs.